1. Field of the Disclosure
Embodiments disclosed herein relate generally to downhole tools, particularly liners and other hydraulically actuated devices. More specifically, embodiments disclosed herein relate to liner hanger flow diverter apparatuses and methods used when running liners.
2. Background Art
Typically, liners are used below casing in wellbores to extend the length of the casing. A liner is a section of smaller casing that is suspended downhole in existing casing. In most cases, the liner extends downwardly into an open hole and overlaps the existing casing by approximately 200-400 ft. In certain application, the liner may be cemented in place. A conventional liner hanger is used to attach or hang liners from the internal wall of a casing segment. The liner hanger is typically connected to a running tool, which in turn is connected to a string of drill pipe extending to the surface. This entire assembly may be run to a bottom of the well, after which the liner is cemented in place.
When running tighter clearance liners down the well, there may not be sufficient space in the annulus between the liner and open hole for the drilling fluid to flow up through the annulus and out of the wellbore. Restricted flow through the annulus may create a positive pressure ahead (or downhole) of the liner called “surge pressure,” which may crack the wellbore formation, causing a variety of problems.
To avoid the surge pressure buildup in the well, a fluid diverter tool may be connected above a liner hanger running tool, which may provide an alternative fluid flow path (e.g., with flow ports) for the escaping fluid by allowing the fluid to flow up a central bore of the fluid diverter tool, past the tighter clearance annulus, and then out into the annulus above the liner. In this manner, the escaping fluid is not forced to flow only through the restrictive annulus formed between the tight clearance liner and the well. By running a fluid flow diverter tool, surge pressure generated may be reduced or eliminated/prevented in the well. When the liner is run to the desired depth in the well, the flow ports in the fluid diverter tool may be permanently closed before cementing operations commence (usually with a dropped ball).
However, there are times when the ports in the fluid diverter tool may need to be closed prior to reaching the desired depth with the liner. For example, at times during running tight liners in the well, there may be an obstruction that hinders the further lowering/running of the liner (e.g., debris, cement plugs, dried mud cake, etc). In such circumstances, drilling fluid may be pumped down the central bore to the bottom of the liner to remove the obstruction. Before pumping down the central bore, the flow ports, which have allowed escaping fluid to flow from inside to outside, must be closed. As before, with current fluid diverter tools, a ball is dropped to build pressure in the bore and shear a pin to close the ports. However, once the ball is dropped and the ports are closed, they cannot be reopened, i.e., this is a one time only operation. Thus, further running of the liner in the wellbore to the desired depth will once again produce surge pressures because the flow diverter ports are closed.
Moreover, the manner in which ball drop mechanisms function may create a surge pressure problem. For example, in certain systems, a ball seat is attached to a piston, which is held in position by shear screws. Once the tool is activated to close the flow ports, the dropped ball remains in place. Pressure is further increased on the upstream side of the ball to the next higher value until a point where the ball extrudes through the ball seat and is blown further downhole. This sudden opening of the central bore of the fluid diverter tool causes the pressure in the central bore to travel downhole and “hit” the formation, essentially creating the same surge pressure problem discussed above.
Accordingly, there exists a need for a fluid diverter tool in which a bypass port may be repeatedly cycled between open and closed positions while in the wellbore as needed.